This proposal is designed to analyze the effects of amphetamine sensitization on dopamine release in the nucleus accumbens in a rodent model of schizophrenia. Research has shown that substance abuse in the schizophrenic population is approximately 2-5 times higher than that of the general public. The abuse of drug in the psychostimulants class, such as amphetamine and nicotine, are the most frequently abused drugs in the schizophrenic population. There is not a definitive explanation as to why there is a high level of drug abuse in this population, as substance abuse in schizophrenia has not been a well-investigated issue. Although there is typically higher overall functioning in women schizophrenics, this disappears with substance abuse, and women are more vulnerable to the negative effects of psychostimulant abuse. The rodent model of schizophrenia utilized in this proposal is based on long-term priming of the dopamine D2 receptor through neonatal administration of quinpirole, a dopamine D2/D3 agonist. Past research has demonstrated that neonatal quinpirole administration produces priming of the dopamine D2 receptor throughout the animal's lifetime. Preliminary data of this proposal demonstrates that an acute injection of amphetamine to D2-primed rats produced a 4-fold increase in dopamine microdialysate in the neostriatum compared to animals non-D2-primed rats neonatally treated with saline. The increase in dopamine release induced by amphetamine may be important in explaining the increased incidence of psychostimulant abuse in the schizophrenic population, and may lead to reduction in anhedonia, a negative symptom of the disorder. The proposal is designed to analyze three specific aims: 1) Compare the effects of amphetamine sensitization and analyze amphetamine's effects on dopamine release in the nucleus accumbens core utilizing microdialysis in D2-receptor-primed versus non-D2-receptor primed rats;2) Investigate the role of dopamine D1 and D2 receptors in sensitization and dopamine release in the nucleus accumbens core in D2- versus non-D2-primed rats;3) Analyze sex differences in amphetamine-induced behavioral sensitization and its relationship to dopamine microdialysis in the NAcc in D2- versus non-D2-primed rats. Plain language description: Schizophrenia affects approximately 1% of the U.S. population, and this population is 2-5 times more likely to use or abuse stimulants than the general public. This proposal is designed to investigate the effects of chronic amphetamine (street name: Speed) administration on behavior and neurochemistry of rats that been given a drug manipulation during development that mimics the neurochemistry of schizophrenia.